Question: In the right triangle shown, $BC = 4$ and $AB = 6$. What is $AC$ ? $A$ $C$ $B$ $?$ $4$ $6$
Answer: We know $a^2 + b^2 = c^2$ We want to find $b$ ; let $a = 4$ and $c = 6$ So $b^2 = c^2 - a^2 = 6^2 - 4^2 = 20$ Then, $b = \sqrt{20}$ Simplifying the radical gives $b = 2\sqrt{5}.$